Question

(a+1/a)² = 9 find (a³+ 1/a³) 2nd question pls pls pls

Answer 1

as (a+1/a)^2 = 9

a+1/a = root 9

a+1/a =3

then, cube on both sides,

by identity (a+1/a)^3  = a^3 +1/a^3 +3(a * 1/a) [a+1/a]

(a+1/a)^3 =3^3

a^3 +1/a^3 + 3(a*1/a) [a+1/a] = 27

now, putting the given values 

a^3 +1/a^3 +3(1)(3) =27

a^3 +1/^3 +9=27

a^3 +1/a^3 = 27-9

a^3 +1/a^3 = 18



i hope this will help you



- by ABHAY

Answer 2

Given (a + 1/a)^2 = 9,

 Then a + 1/a = 3  ----- (1)

We know that (a^3 + b^3) = (a + b)^3 - 3ab(a + b)

(a^3 + 1/a^3) = (a + 1/a)^3 - 3 * a * 1/a (a + 1/a)

                     = (3)^3 - 3(3)

                      = 27 - 9

                      = 18.


Therefore the value = 18.


Hope this helps!